Rochester Monojet Help

[ST Dog]

Originally Posted by 68gmsee

Here's a bump for you...

I've got a Rochester monojet with manual choke on my 68 GMC. I'm not sure how much of a difference there was in the linkages between the early and later years, but I can post a pic later tonight.

Is the choke linkage and fast idle cam the only pic you need?

I think so, the rest seams OK. I just want to verify that everything is there, or figure out what's missing.

[68gmsee]

Well, the pics I took looked like crap so I'll get some with a different camera tomorrow morning.

[68gmsee]

Here's a pic. Hope it helps.

[ST Dog]

Quite different. Here's what I have.


(Hard to fit my camera in there for a good picture)

I guess it's all there. I adjusted the linkage from the choke to the fast idle cam so that it pulls the cam all the way at full choke.
Then adjusted the tang closed to that cam to touch and set the fast idle. About 2000 rpm when warmed up at the position the cam goes to for full choke.

[68gmsee]

Actually they're pretty simlar... Your setup is the way my original carb was. I did some swapping out last year but still have all the original stuff except for the oil breather- must have gotten left behind in one of my moves.

The tang is adjusted so that it has a slight clearance when the choke is fully open. As you engage the choke, the lever pulls up on the bellcrank to increase the throttle opening.

When you push the choke in, the bellcrank should "free fall" to it's normal rest position.. Very simple mechanism, but works great!

forgot to add: on mine, the link pushes the bellcrank down as opposed to free falling.

[ST Dog]

Originally Posted by 68gmsee

Actually they're pretty simlar... Your setup is the way my original carb was. I

Well, I think there's a lot of difference. The curb idle adjustment is different, the fast idle cam is different, and the tang on the throttle shaft is different.

I'm even more confused as to the origins of this carb though. Looks to be cobbled together parts from the original '68 carb and the '72/'73 carb indicated by the number stamped on it.

At least it seams to work now. Best I can tell, it has never worked. No way the linkage/tang has worn that much. No signs of wear either.

Now at least I can get a fast idle to warm the engine up. I need to go through the carb though, as it need a few minutes of warm up before it's drivable, eevn in 80* weather.

Thanks for the help. I feel better about the adjustments. Only carb I know well is the Q-Jet from late 60s/early 70s Cadillacs (divorced choke).

[cdowns]

try going to a public library and see in they have any haynes ,motors,or chiltons manuals either of those 3 should have good info on that carb

have you done the basics like sparkplugs and points //those are a good first step b4 jumping on the carb bandwagon// fuel and air filters too

[68gmsee]

You got me there sarge... I guess if you look at the little things they are different. I was mainly refering to the operation: link, bellcrank, manual choke.

What you have is probably an M/MV series out of a newer vehicle with idle "speed control" where the idle adjustment screw is. My book shows yours to be sort of a combination of different carbs.

Gotta remember that when these carbs were sent back for rebuilding they used whatever parts they could find. Since a lot of the parts were interchangeable, they used newer and older parts to make them work.

The bellcrank "hook" was there on some vehicles so that if you stomped on the throttle it would force the choke open.

But, glad you got it going though. Let me know if you need anymore pics.